The workers also suffered physical beatings in high numbers: Almost 70 per cent reported being bashed in the past year, most often from relatives (43 per cent), but also their husbands (27 per cent) and others they knew.

With the ever-present threat of HIV/AIDS - the most recent reports suggest rates are increasing at almost 30 per cent year in parts of PNG - Bertha's safe sex advice could be the difference between life and death for vulnerable girls whose own families and loved ones have turned their backs on them.

She barely left her house during daylight hours for several months. A woman looks down the valley from Kassam Pass, Morobe Province.

She was accepted back by the villagers but never received an apology from her attackers. The beautiful landscape of Papua New Guinea’s highlands belies the brutal reality of life in the region, where more than 90 percent of women report suffering gender-based violence.

Despite the ever-present threat of HIV/AIDS, with the most recent reports suggest rates are increasing at almost 30% a year in parts of PNG, grinning potential customers wait to take the young sex workers to a private room 'If a girl goes skin-on-skin she is not thinking about her life,' says Bertha.

But she also points out that many girls who insist on using condoms will simply be raped without one anyway, and often beaten up as well.

She is saving as much as she can from her earnings and plans to start her own business selling sweets, betel nut or cigarettes.

In the meantime, she has regular blood tests and counselling at the children's charity where Bertha volunteers.

Alai was arrested by police, however after receiving treatment Helen left her home out of fear that her husband might be released.